Newbie with question on humidity

How high should my humidity be and is it important? First time growing photos and all new equipment. Here is what I’m working with.

  1. 5’x5’ mars hydro tent
  2. [email protected] Hlg qb288 v2 Rspec boards
  3. 600 watt meanwell driver
  4. 6" infinity exhaust fan
  5. Fox Farm ocean floor (perlite and worm castings added)
  6. [email protected] Bruce Banner’s from homegrown cannabis co
  7. floraflex style watering system
  8. secret jardin monkey fan


Welcome to The Forum this is a great place to learn. And yes humidity does matter to a certain extent. There are Growers here who can give you everything you need to know about the humidity but not me LOL I’m a pretty novice indoor grower myself I’ve only been doing it for a little over a year. But stick around you will get the info you need and hope to see you here for a while. Peace and happy growing


@brucealmighty To awnser your question yes humidity plays a large role in how your plants breath and move nutrients from the soil to were they need to go. Also to high a humidity makes for an unhealthy environment for your plants. The stage your plants are in 40 to 60% should work. I am sure someone will link you to were the subject is discussed in deapth.


@brucealmighty humidity is important as the wrong humidity at certain stages can stunt growth, cause nutrient issues, root issues, and mold issues.

During seedling stage 70-90% humidity is needed for proper development because seedlings don’t have a lot of roots so they get most of their water via the stomata and drink it from the air. Vegetative 50-60% is ideal because it keeps them from transpiring and dehydrating. More can cause wilting and mold, less can cause wilting and dehydration. During flower 30-40%. This is to prevent mold but also to simulate the dry cool air of fall and winter so the buds produce more resin and ripen.


Welcome to the forum @brucealmighty
Humidity and temp are both important and closely related as well as the each affect the other. Here is a VPD chart to help you out. VPD is something you should learn about and how it affects your plants transpiration.


And that’s a beautiful set up you got there. Keep us updated on the grow.


That chart just confuses me. What is the purpose of the chart I know it’s VPD or whatever but what is that and how do I read that chart? So if I’m running a plant 72 degrees 36% humidity It says that I’m between 1.03and 1.14 If I’m reading that right that’s not too bad correct? they are 5 weeks from flip and probably three weeks from flowering start.

@Rye that helps explain VPD quite a bit thanks.

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@dmtscravey with this chart you want to be in the green, blue, and purple zones. The red zones can effect growth negatively. So yeah 72 degrees F at 36% humidity during flower is in the healthy ranges.

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I have been running from 31% to 33% so it looks like I will be investing in a humidifier it shouldn’t take a very large unit for a grow tent. Thanks for all the information


@brucealmighty a couple tips on your humidifier. Get a true ultrasonic one, not one that uses a wick. Make sure to part that hold water is light proof, or you will grow algae. Use CLEAN water, the cleaner/purer it is the less you have to clean/decalcify it. Dont let it blow directly on the plants.

Having said all that serious stuff, theres a really cool green frog humidifier that fits the bill perfectly and it’s a FROG. Someone on here has one in their room. It may be smaller but is a FROG.


frog humidifier $11.99 at Manards sounds cheap enough